Electronic products such as a digital television (TV), a smartphone, a laptop computer, and the like typically transmit and receive data in a high frequency band. In the future, it is expected that such information technology (IT)-based electronic products will not only be used as individual devices, but will also be connected to one another through communications ports such as, for example, the universal serial bus (USB) connections, such that they will perform multiple and complex functions.
In accordance with the development of the smartphone, demand for a thin power inductor having a high current, high efficiency, high performance, and a small size has increased.
Therefore, products having a 2520 size and a thickness of 1 mm to a 2016 size and a thickness of 1 mm have been used, and have been miniaturized to a product having a 1608 size and a thickness of 0.8 mm.
At the same time, demand for an inductor array having an advantage, such as a smaller mounting area, has also increased.
The inductor array may have a non-coupled or coupled inductor form or a mixture of the non-coupled inductor form and the coupled inductor form, depending on a coupling coefficient or mutual inductance between a plurality of coil parts.
Meanwhile, in coupled inductors, leakage inductance is associated with an output current ripple, and mutual inductance is associated with an inductor current ripple. In order for the coupled inductor to have the same current ripple as that of the existing non-coupled inductor, the leakage inductance of the coupled inductor may be matched with an inductance of the existing non-coupled inductor. In addition, when the mutual inductance is increased, the coupling coefficient k is increased, such that the inductor current ripple may be reduced.
Therefore, in the case that the inductor current ripple is reduced while the coupled inductor having the same output current ripple as that of the existing non-coupled inductor at the same level as that of the existing non-coupled inductor, efficiency may be increased without increasing a mounted area.
Therefore, in order to increase the efficiency of the inductor array while maintaining a size of the inductor array, providing a coupled inductor of which a coupling coefficient is increased by increasing mutual inductance is desirable. In addition, in the coupled inductor, an interval between coils may be decreased in order to increase the coupling coefficient. However, there may be issues in a process of decreasing the interval. Therefore, a method of increasing the coupling coefficient between the coils while overcoming the limitation in the process described above is desirable.